Wrap/break equations text when exporting to PDF

So I just finished writing my homework in Lyx and I was about to print it after exporting to PDF, but I noticed that some of the centered equations were too long and their most-right part is exceeding the right margin of the PDF page.

I saw that I can use AMSmath to solve it but for that it seems like I need to manually copy all of the equations to AMSmath boxes.

Is there any way to solve it with a quick PDF-export preprocess? edit some setting?

This is one of the long equations (gaussian elimination):

\L{
$\left(\begin{matrix}0 & 0 & 0\\ 2 & 0 & 2\\ 8 & 0 & 2\\ 18 & 0 & 2 \end{matrix}\right)\to\left(\begin{matrix}0 & 0 & 0\\ 1 & 0 & 1\\ 4 & 0 & 1\\ 9 & 0 & 1 \end{matrix}\right)\to\left(\begin{matrix}0 & 0 & 0\\ 1 & 0 & 1\\ 4 & 0 & 1\\ 5 & 0 & 0 \end{matrix}\right)\to\left(\begin{matrix}0 & 0 & 0\\ 1 & 0 & 1\\ 4 & 0 & 1\\ 1 & 0 & 0 \end{matrix}\right)\to\left(\begin{matrix}0 & 0 & 0\\ 1 & 0 & 1\\ 0 & 0 & 1\\ 1 & 0 & 0 \end{matrix}\right)\to\left(\begin{matrix}0 & 0 & 0\\ 0 & 0 & 1\\ 0 & 0 & 1\\ 1 & 0 & 0 \end{matrix}\right)\to\left(\begin{matrix}0 & 0 & 0\\ 0 & 0 & 0\\ 0 & 0 & 1\\ 1 & 0 & 0 \end{matrix}\right)\to\left(\begin{matrix}1 & 0 & 0\\ 0 & 0 & 1\\ 0 & 0 & 0\\ 0 & 0 & 0 \end{matrix}\right)$
}


and as you can see in the PDF it's being cut right before the end: thanks...

• Better than you add your PDF result too, so we can see the problem clearly. – Kurniawan Prihadi Oct 29 '17 at 18:49
• Does Lyz support \usepackage{showframe} ? – John Kormylo Oct 30 '17 at 14:45

Just use \multline in package amsmath to divide long expressions taking more than one line.

\begin{multline}
a+b+c+d+e+f+g+h+i+j+k+l+m\\
+n+o+p+q+r+s+t+w+x+y+z=0
\end{multline}


It will divide that long equation into 2 line.

Or you can use gather environment (gather*) if you need a non-numbered equation).

\documentclass{article}

\usepackage{amsmath}

\begin{document}

\begin{gather*}
\left(\begin{matrix}0 & 0 & 0\\
2 & 0 & 2\\
8 & 0 & 2\\
18 & 0 & 2
\end{matrix}\right)\to\left(\begin{matrix}0 & 0 & 0\\
1 & 0 & 1\\
4 & 0 & 1\\
9 & 0 & 1
\end{matrix}\right)\to\left(\begin{matrix}0 & 0 & 0\\
1 & 0 & 1\\
4 & 0 & 1\\
5 & 0 & 0
\end{matrix}\right)\to\left(\begin{matrix}0 & 0 & 0\\
1 & 0 & 1\\
4 & 0 & 1\\
1 & 0 & 0
\end{matrix}\right)\to\\ %<= this where the eq will be splitted
\left(\begin{matrix}0 & 0 & 0\\
1 & 0 & 1\\
0 & 0 & 1\\
1 & 0 & 0
\end{matrix}\right)\to\left(\begin{matrix}0 & 0 & 0\\
0 & 0 & 1\\
0 & 0 & 1\\
1 & 0 & 0
\end{matrix}\right)\to\left(\begin{matrix}0 & 0 & 0\\
0 & 0 & 0\\
0 & 0 & 1\\
1 & 0 & 0
\end{matrix}\right)\to\left(\begin{matrix}1 & 0 & 0\\
0 & 0 & 1\\
0 & 0 & 0\\
0 & 0 & 0
\end{matrix}\right)
\end{gather*}

\end{document}


I think this is not bad to show the Gaussian Method.

• But it means I have to add these tags for every single equation in my document, right? – gbi1977 Oct 29 '17 at 19:13
• @gbi1977 yes of course, you can also use gather environment to get same as multline but the splitted equation will be centered. You can check amsmath documentation for more information. – Kurniawan Prihadi Oct 29 '17 at 19:21
• I acutally used all of these environments right now and it still won't help, the equations exceed the right margin. the best way I found is to add a new line with CTRL+ENTER and copy to tail of the eqaution there. But I thought there should be at least one simple setting to wrap the eqautions during pdflatex export... – gbi1977 Oct 29 '17 at 19:24